Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <bits/stdc++.h>

using namespace std;

int main(){
  int h, w;
  cin >> h >> w;
  string s[h];
  for(auto&& ss:s)cin >> ss;
  const int INF = 100000;
  vector<vector<int>> d(h, vector<int>(w, INF)); 
  d[0][0] = 0;
  queue<pair<int, int>> q;
  q.emplace(0, 0);
  const int di[4] = {1, -1, 0, 0};
  const int dj[4] = {0, 0, 1, -1};
  while(!q.empty()){
    int i = q.front().first, j = q.front().second;
    q.pop();
    if(i == h-1 && j == w-1)break;
    for(int k=0;k<4;k++){
      int newi = i + di[k], newj = j + dj[k];
      if(newi < 0 || newi >= h || newj < 0 || newj >= w)continue;
      if(s[newi][newj] == '.' && d[i][j] + 1 < d[newi][newj]){
        d[newi][newj] = d[i][j] + 1;
        q.emplace(newi, newj);
      }
    }
  }
  if(d[h-1][w-1] == INF)cout << -1 << endl;
  else{
    int sh = 0;
    for(auto&& ss:s)for(auto&& c:ss)sh += (c == '#');
    cout << h * w - sh - d[h-1][w-1] - 1 << endl;
  }
}